拟南芥MicroRNA通路一个新因子的鉴定和功能研究
发布时间：2018-10-05 12:54
【摘要】：RNA干扰(RNA interference, RNAi)是一类真核生物中保守的调控基因表达的机制。RNAi中的核心组分是small RNAs (sRNAs)和Argonaute (AGO)家族蛋白。sRNAs同AGO蛋白结合形成RNA-induced silencing complexes (RISCs)。RISCs在sRNAs的介导下通过碱基互补配对的方式在转录水平(Transcriptional gene silencing, TGS)或者转录后水平(Post-transcriptional gene silencing, PTGS)特异调节基因的表达。在拟南芥中,根据sRNAs的生成和作用机制的不同,将其分为四类,包括microRNAs (miRNAs), trans-acting sRNAs (ta-siRNAs), natural antisense siRNAs (na-siRNAs)和heterochromatin siRNAs (hc-siRNAs)。miRNAs是一类长度为21 nt的sRNAs,它在植物的多种生物学过程中起着重要的作用。miRNAs的表达具有组织和发育的特异性。在拟南芥中,miRNAs基因由RNA聚合酶Ⅱ(RNA polymerase Ⅱ, Pol Ⅱ)转录得到初级miRNAs (primary miRNAs, pri-miRNAs), pri-miRNAs具有一个发卡结构。RNA结合蛋白DAWDLE (DDL)可以结合和稳定pri-miRNAs,并且招募Dicer-like 1 (DCL1)去识别和切割pri-miRNAs。DCL1在双链RNA结合蛋白HYPONASTC LEAVES 1 (HYL1)和锌指蛋白SERRATE (SE)的协助下,将pri-miRNAs准确有效的切割成为成熟的miRNAs。DCL1, HYL1和SE在细胞核内形成一个切割复合物,被称为Dicing-bodies (D-bodies)。成熟的miRNAs进入到AGO1蛋白中,通过切割靶基因的mRNA或者抑制其翻译来调节基因的表达。为了加深我们对miRNA通路机制的理解,我们利用一个高效表达可使拟南芥表皮毛成簇的人工miRNA的转基因系,建立了针对miRNA通路的遗传筛选体系。通过诱变筛选,我们得到了一些miRNA活性增强(enhanced miRNA activity, ema)或减弱(compromised miRNA activity, cma)的突变体。我们之前报道的EMA1编码一个importin β家族蛋白,可以负调节miRNA进入AGO1的过程。在本研究中,我们进一步以emal突变体为材料,进行了emal的抑制子筛选(suppressor of emal, soe),以更敏感地获得调节miRNA产生和活性的新因子。在本研究中,我们分析了其中一个突变体soe4。该突变发生在AT2G19380中。AT2G19380编码一个包含四个锌指结构域和一个RNA结合结构域(RRM)的未知功能蛋白。soe4突变中成熟miRNA和pri-miRNA的积累量均下降。SOE4定位于D-body中,且能够与D-body组分DCL1,HYL1和SE相互作用。此外,SOE4在体外可以还结合pri-miRNA和pre-miRNA。我们的研究结果表明,SOE4在拟南芥miRNA通路中可能作为miRNA前体的结合蛋白起着稳定pri-miRNA或者pre-miRNA的作用。
[Abstract]:RNA interference (RNA interference, RNAi) is the mechanism of conserved regulation of gene expression in eukaryotes. The core component of RNAi is the binding of small RNAs (sRNAs) and Argonaute (AGO) family proteins to AGO proteins to form RNA-induced silencing complexes (RISCs) .RISCs mediated by sRNAs. Pairings take place at the transcriptional level of (Transcriptional gene silencing, TGS) or at the post-transcriptional level (Post-transcriptional gene silencing, PTGS) specifically regulates the expression of genes). In Arabidopsis thaliana, according to the formation and mechanism of sRNAs, it is divided into four categories. MiRNAs including microRNAs (miRNAs), trans-acting sRNAs (ta-siRNAs), natural antisense siRNAs (na-siRNAs) and heterochromatin siRNAs (hc-siRNAs). MiRNAs are a class of 21 nt sRNAs, which play an important role in many biological processes of plants. The expression of miRNAs has tissue and developmental specificity. In Arabidopsis thaliana, the miRNAs gene is transcribed by RNA polymerase 鈪，
本文编号：2253461
[Abstract]:RNA interference (RNA interference, RNAi) is the mechanism of conserved regulation of gene expression in eukaryotes. The core component of RNAi is the binding of small RNAs (sRNAs) and Argonaute (AGO) family proteins to AGO proteins to form RNA-induced silencing complexes (RISCs) .RISCs mediated by sRNAs. Pairings take place at the transcriptional level of (Transcriptional gene silencing, TGS) or at the post-transcriptional level (Post-transcriptional gene silencing, PTGS) specifically regulates the expression of genes). In Arabidopsis thaliana, according to the formation and mechanism of sRNAs, it is divided into four categories. MiRNAs including microRNAs (miRNAs), trans-acting sRNAs (ta-siRNAs), natural antisense siRNAs (na-siRNAs) and heterochromatin siRNAs (hc-siRNAs). MiRNAs are a class of 21 nt sRNAs, which play an important role in many biological processes of plants. The expression of miRNAs has tissue and developmental specificity. In Arabidopsis thaliana, the miRNAs gene is transcribed by RNA polymerase 鈪，
本文编号：2253461
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